Frequently Asked Questions
Internal and external power.
Internal and external power
Instruments with an external data connection, such as RS-232 or RS-485 (FD) include the option of externally powering the instrument.
Choose the right sensor.
Choosing the right sensor for your application
At the time of manufacture, we can use any one of the following options for the depth channel:
- For the plastic case, select from 0 to 20, 50,100, 200, 500, or 1000 (all in metres of water). Please note the plastic housing itself has a maximum pressure range of 740m, so even though a 1000m transducer may be selected, the maximum depth of deployment will be 740m to avoid breaching the housing.
- For the titanium case, select from 0 to 1000, 2000, 4000, 6000 or 10,000 metres
These are all nominal full scale ranges, and the accuracy of the pressure measurement will be 0.05% of this full scale range. For example, if you have a full scale of 500 metres, the accuracy of the pressure measurement is 0.05*500/100 or 0.25m.
The selection is complicated by another factor: each range has a maximum beyond which it should not be used. This is called the “proof pressure”, and it is the range up to which the pressure sensor can be deployed without causing permanent damage to the transducer. Between the full scale pressure and the proof pressure, the sensor may or may not function properly, but once the instrument returns to a depth shallower than the full scale range, normal operation will resume.
|Full Scale Range (m)||Absolute Maximum Pressure (m)|
|500||740 (limited by housing)|
|1000 (plastic)||740 (limited by housing)|
Sometimes there are different terms which mean the same thing. Turbidity is a quantity measured by optical back-scatter of light and OBS stands for Optical Back-Scatter. TSS or Total Suspended Solids is also a quantity measured using optical back scattering.
Turbidity and TSS are essentially the same parameter. Although turbidity purports to measure approximately the same water quality property as TSS, the latter is more useful because it provides an actual weight of the particulate material present in the sample. The relationship between turbidity and TSS (total suspended solids) depends on the nature of the solids, but all turbidity sensors measure optical back scatter.
Here is the description from the Seapoint site:
“The Seapoint Turbidity Meter is a very low-power, miniature sensor that detects light scattered by particles suspended in water, generating an output voltage proportional to turbidity or suspended solids.”
And here is the description from the D&A site:
“The OBS®-3+ sensor measures suspended solids and turbidity by the optical back-scatter method (ASTM 6677). It features a compact micro probe that responses almost linearly over a 1000-fold change in sediment concentration (SSC) and turbidity.”
It amounts to exactly the same thing. The responsibility for calibration from turbidity to TSS in either case rests with the user.
It depends on your application and budget. Both the galvanic cell sensor and the optode sensor are accurate instruments. The optode is more expensive than the galvanic cell sensor, but long term can be more stable, and does not require periodic refurbishment and recalibration. The Oxyguard has a lower initial cost, but does require periodic refurbishment and recalibration by the end user to ensure it is accurate measurements. Normally for short duration deployments we recommend the galvanic sensor, but for deeper and longer deployments, we recommend the optode.
Yes we offer two types, one is a strain gauge and the other is a quartz crystal. The strain gauge is what we recommend for most applications as it has an accuracy of 0.05% full scale accuracy, while the quartz sensor has an accuracy of 0.01% full scale. So depending on the accuracy of the depth you need the choice should be based on these characteristics.
When we can we try to offer sensors in different price and accuracy categories or for special purposes.
In the case of the DO sensors we offer a Galvanic cell sensor and an Optode. The galvanic cell sensor is less expensive than the optode but requires more routine maintenance to keep it operating effectively.
With regard to the fluorometers, our standard offering is either the Turner Cyclops-7 and the Seapoint fluorometer. The selection depends on the depth rating required 6000m or 600m and the range (µg/l) of the measurement (up to 150 µg/l or 500 µg/l), as well as pricing and power requirements. The Turner sensor is a less expensive sensor, but does have higher power requirements which would limit possible deployment life for deployments without external power supply to the instrument.
Logger differences and configurations.
Configuration options and their availability
RBR prides itself on the flexibility of its products. While not all configurations are possible due to mechanical or electronic requirements, we are happy to review any sensor requirements to determine feasibility.
Ruskin, its predecessors, and more.
RBR Ruskin Software and its predecessors
The firmware on our latest generation of instruments (RBRvirtuoso/duo/concerto/maestro, RBRsolo/duet) is field upgradable through our Ruskin software. If you are running Ruskin on a computer connected to the internet, and plug in a logger, Ruskin will automatically check if a new firmware version is available, and will ask you if you would like to upgrade your logger. You can also manually upgrade the firmware in Ruskin, under the Instruments menu, select Upgrade logger firmware.
Firmware updates for legacy instruments such as the XR series or TDR instruments may not be possible depending on the age of the instrument. If the firmware can be updated, it will require the instrument to be returned to the factory, and the upgrade would be a chargeable service item.